1. Field of the Invention
The present invention relates to a method for recycling synthetic wood materials from sheathing board for use in a concrete form made of synthetic wood materials, and a sheathing board for use in concrete form having these recycled synthetic wood materials as raw materials, and a technique for recycling sheathing board which is as lightweight as sheathing boards made of plywood, having an adequate workability and being convenient to handle, having a sufficient strength for use as a concrete form and which can be regenerated by retransforming into materials after use.
2. Description of the Related Art
As a general concrete form currently in use, there is the form made of plywood which uses plywood as the sheathing board. In this form made of plywood, although labor is expended to improve the finishing of the concrete surface, such as coating the surface of sheathing board with oil or synthetic resin, a sheathing board made of plywood has a relatively light weight and has considerable workability when transporting and installing, while at the same time, it has a considerable workability such as cutting, and, having an adequate heat retaining property towards concrete, it exhibits an excellent efficacy for casting concrete in the winter.
Such plywood which forms the sheathing board of the plywood form has natural wood as raw materials. However, according to the 1987 “Forest Products Statistics” by FAO, the gross wood export volume from the tropical rain forest region was approximately 7,700 ml, of which Japan imported 27% as 2,200 m3 of South Sea wood, and 76% of this imported South Sea wood was consumed as plywood. Such environmental destruction has been the cause of problems, such as global warming, due to the deforestation of the rain forest region which is consumed in large quantities in this way. Therefore, the amount of consumption of natural wood being used for plywood should be decreased.
As a result of such a requirement, plywood forms are repeatedly used several times, in an attempt to realize effective use. However, to reuse a previously used plywood form, a so-called “Surface cleaning operation” needs to be performed, which consists of removing the concrete encrusted on the surface of the form with a brush or a spatula. This activity is complex.
In addition, forms which have been, for example, cut and worked to match the working place, the fragments of these forms, furthermore, among the forms which have been repeatedly used as described previously, those which have exhausted their lives as forms due to chipping and deformation, can not be regenerated and reused in the same way as, for example, resin materials are, and are ultimately disposed of. Therefore, from the standpoint of the conservation of the natural environment, the appearance of a sheathing board for use in concrete forms is in demand, obviously usable over several times, and made of materials which are recyclable by, for example, transforming into materials after their lives as concrete forms have been exhausted.
As such sheathing boards made of materials other than plywood, metal forms and forms made of resin exist.
In the above description, the metal form is considerably more rigid when compared to the plywood form, with only slight chipping and deformation, and can sustain repeated use. However, this metal form is heavier in comparison to the form made of plywood, and does not allow for operation with human power in cases such as transport, installation and uninstallation. In addition, workability such as cutting is not adequate and its handling is difficult.
In addition, the metal form is easily influenced by external temperatures, has an inadequate heat retaining property towards concrete, and is not as suited as the plywood form to operation in the winter. Also, the concrete surface may become stained by corrosion.
In addition, as with the previously described plywood form, in order to improve the mold releasing property, it needs to be coated with oil or synthetic resin mold release agent. Also, to reuse a metal form once it has been used as a form, a Surface cleaning operation is necessary to remove the concrete encrusted on its surface with a brush or a spatula.
Thus, when compared to the previously described form made of plywood, the metal form is inconvenient to handle, and does not have the quality of a concrete form replacing the form made of plywood.
A form made of resin has been proposed as a concrete form which solves the shortcomings of the metal form such as the ones described above, and replaces the form made of plywood (for example, Kokai No. Hei. 6-88421, Kokai No. Hei. 8-23038).
This form made of resin has fiber reinforced plastic as raw materials, wherein plastic such as polypropylene is reinforced with glass fibers, and strength is added to sustain the pressure produced when casting concrete, by placing on one side of the sheathing board, several ribs with a height of approximately. 60 mm, parallel to the direction of the length of the sheathing board.
This form made of resin is lightweight, has considerable workability such as cutting, and allows for easy handling, when compared to the previously described metal form.
However, cutting this form made of resin, reinforced with, for example, glass fibers, requires that a chainsaw for plastic be used, and at the same time, in the case of such a processing operation, the scattered glass fibers may adhere to the clothes and the skin, accompanied by severe pain and itching.
In addition, the opening formed on the sheathing board for mounting the separator must be formed monolithically when casting the sheathing board made of resin. Therefore, with this kind of sheathing board, the degree of freedom for working in the field is low.
In addition, concerning the previously mentioned sheathing board made of resin, since, as previously described, it comprises ribs having a relatively thick thickness of greater than 60 mm to maintain its strength, it is a voluminous item for transportation and storage.
Further, once the sheathing board has been used as a concrete form, its surface is encrusted with large quantities of exogenous materials such as concrete and gravel. To transform the broad into materials and regenerate a board, it is necessary to perform the elimination of exogenous materials, by eliminating the encrusted materials such as concrete and gravel with a brush and a spatula, and by further washing the surface of the form after elimination. A large amount of labor and expense is expended for this operation, and constitute the weak points of the recycling and regeneration of the sheathing board.
In addition, as previously described, when washing sheathing board, the waste water generated during the washing must be treated appropriately, which requires an installation and labor.
Consequently, the object of the present invention, is to solve the above mentioned shortcomings of the prior art, a further object of the present invention is to achieve an effective utilization of resources as well as an improvement of the natural environment by providing a method for obtaining raw materials from a transformation into materials, through a relatively simple method, without eliminating, using a brush and a spatula, encrusted materials such as concrete, which are encrusted on the surface of a sheathing board, used in a concrete casting operation, and without washing, and by providing at the same time, a method for regenerating a sheathing board again from these obtained raw materials, promote the reuse of sheathing boards, and decrease the amount of usage of sheathing boards made of plywood having natural wood as raw materials.
In addition, another object of the present invention is to achieve an effective utilization of resources as well as an improvement of the natural environment by providing a sheathing board which is as lightweight as a sheathing board made of plywood, has adequate workability and is convenient to handle, at the same time having sufficient strength to be used as a concrete form, which can further be regenerated after use, by transforming again into materials, and decreasing the amount of usage of sheathing boards made of plywood having natural wood as raw materials.